File:Ocean City Maryland Lifeguard Hurricane Earl.jpg|thumb|right|A lifeguard (USA) on patrol during Hurricane Earl (2010)|Hurricane Earl.
File:RedYellowFlag.jpg|thumb|right|upright|Red and yellow flag indicating a bathing area patrolled by lifeguards.
A '''lifeguard''' supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool
, water park
, or beach
. Lifeguards are strong swimmers and trained in first aid
, certified in water rescue using a variety of aids and equipment depending on requirements of their particular venue. In some areas, lifeguards are part of the emergency service
s system to incidents and in some communities, the lifeguard service also carries out mountain rescues, or may function as the primary Emergency medical service|EMS